Is there an official direction for scroll zoom?

Question

I am using a Magic Mouse on Lion and I have scroll direction set to natural.

• Google Maps: Scroll Up zooms out
• Excel: Ctrl + Alt + Scroll Up zooms out
• OSX Zoom Dekstop: Ctrl + Scroll Up zooms in

I find the inconsistency annoying.

Thus, I'm wondering whether Apple has an official usability rule regarding what direction constitutes the recommended scroll direction for zoom in?

Answer 1

If natural scrolling is disabled, scrolling up zooms in in all of those three cases. Scrolling up zooms in the screen even if natural scrolling is enabled though.

Scrolling while holding control could be considered to be a separate gesture where enabling natural scrolling does not invert the scrolling direction. When using a multi-touch surface, I think it's more natural that dragging up increases the zoom level.

It's also possible that applications shouldn't invert the scrolling direction when scrolling is used for zooming, but many applications do. But I didn't find anything about it in the HIG, and I don't know any applications by Apple where scrolling while holding option or command would have a special meaning.